I have watched enough bulk cable gland enquiries stall at the quotation stage to know the failure point is rarely the supplier. Explosion proof cable glands for a multi-line order need the same discipline as a valve or instrument package: a full cable schedule, a defined certification path, and entry data that matches the installation. RFQs that arrive as a part number and a quantity place the whole technical risk on the vendor. Buyers who specify the hazardous area data, cable construction, thread standard, and documentation requirements get comparable bids and fewer post-order replacements. This article sets out the fields I would want to see before quoting a bulk gland package.
Hazardous Area Data for an Explosion Proof Cable Gland RFQ
Start the RFQ with the installation boundaries, not the gland list. State the zone, gas group, temperature class, and protection concept for each area where the glands will be installed. A single project can combine Zone 1 storage, Zone 2 utilities, and a dust zone in a milling area, and the same gland size may not cover all three. When the seller has to infer this from a project name, the quote either carries risk contingency or comes back with a long clarification list.
Split the requirements into site-wide and line-item fields. Replace the phrase “certified for hazardous area” with the named scheme and marking. For IECEx packages, a manufacturer may reference a family such as DQM-III with certificate IECEx TUR 22.0035X and Ex db IIC Gb marking for M and NPT threads, IP66, and an ambient range of -60°C to +90°C. An ATEX package may carry TUV 22 ATEX 8855X under EN 60079-0, EN 60079-1, EN 60079-7 and EN 60079-31. A North American package may require NEC/CEC data and NPT threads. Those few lines are cheaper to write than the rework they prevent.
| RFQ field | What to specify | Common error |
|---|---|---|
| Entry thread | Metric M20 or M25 series, or NPT size for each line | Writing “standard” and assuming the supplier knows the location |
| Cable construction | Armoured, braided, screened or unarmoured; outer sheath diameter range | Missing the inner bedding or screen diameter |
| Hazardous area classification | Zone, gas group, temperature class and protection concept | Repeating a blanket certification without zone mapping |
| Certificate required | IECEx, ATEX, NEC/CEC or project-specific approval | Asking for “certified” without naming the scheme |
| Quantity per size | Per thread size and cable range, plus spare glands | Combining total quantity without a size breakdown |
| Delivery schedule | Partial shipments by area or package, with documentation deadline | Requesting all at once despite phased construction |
Cable Construction and Explosion Proof Gland Matching Rules
The cable schedule is the part of the RFQ that decides whether the quote is firm or conditional. For every line, state the cable outer sheath diameter, the inner bedding diameter if present, armouring type and dimensions, and whether the cable has a screen, braid, or filler. A gland that seals an unarmoured cable may not clamp a wire braid. A gland that clamps steel wire armour may not seal a screened instrument cable without an additional entry component. When the RFQ lists only the cable OD and the part number, the supplier has to assume which construction detail matters, and the buyer inherits that assumption.
Armoured cables need the armouring dimensions stated separately from the sheath OD. For single wire armour, the gland specification should say whether the entry needs an armour cone and a seal boot or a compound barrier. That decision comes from the cable construction and the installation, not from the gland series alone. Unarmoured and screened cables need the screen termination method declared because it changes the gland arrangement and the earthing path.
If the package includes NPT entries for a US or Middle East scope, the thread standard should be explicit rather than assumed. <NPT Explosion Proof Cable Glands for US & Middle East Projects> covers why NPT entries are treated differently and how the matching cable range changes the gland selection.
If the package mixes armoured SWA feeders and unarmoured instrument cables across one bulk order, it is worth confirming whether every entry needs an Ex d flamepath or an Ex e sealing arrangement before the RFQ is issued. Send the cable schedule to gm*@***om.com and we will check entry size, gland type, and certificate coverage for each line.
Certification and Marking Evidence to Request Up Front
Request a certificate list tied to each line item, not a general statement that the company holds the correct approvals. The list should show the certificate number, the issuing body, the marking printed on the gland, and any special conditions for safe use. IECEx and ATEX product family certificates may cover a range of sizes, but the RFQ should ask the bidder to confirm which entries in that range fall under the certificate. That prevents a certificate for one size being assumed to cover the whole order.
Pay attention to the X suffix. An IECEx or ATEX certificate ending in X carries attached conditions. Those conditions can restrict cable types, fix the sealing components, or change the installation requirements. A credible bidder should state those restrictions in ordinary language inside the quote. If the bidder cannot, the package has not been reviewed by an engineer. Also ask whether certificates and the declaration of conformity will be supplied as controlled PDFs before shipment. For bulk deliveries, the site receiving team often needs the file package before the boxes arrive.
Packaging and Documentation Rules for Bulk Delivery
A bulk gland order should be packed so the site can receive it without a full unpack. Specify that line items be packed by size and thread type, with the gland size, thread standard, and certificate reference on each carton label. Mixed cartons slow mechanical completion and raise the chance that a Zone 2 gland ends up in a Zone 1 package. The packing list should follow the same line-item numbering as the RFQ so the receiving inspector can match each box to the approved schedule.
State whether the order includes spare sealing elements, O-rings, and locknuts. On an offshore or remote site, these small parts are hard to source separately, so adding a small spare package by size can reduce downtime. The documentation requirement should also be explicit: request material certificates for metallic parts, the certificate list, installation instructions, and any required inspection reports with each shipment. Without that clause, bidders do not all price the same document package, and the comparison becomes uneven.
Bulk gland orders also need a defined document and packing scope, because bidders do not all price the same package. <Explosion Proof Equipment Cost: Understanding Investment Drivers> explains how certification scope, material grade, and factory testing affect total installed cost rather than just the purchase line.
Firm Quote Requirements for Bulk Explosion Proof Cable Gland Orders
When the RFQ stops at a part number and a quantity, the vendor must either hold price contingency or exclude scope such as documentation, packaging, or partial shipment. That does not produce a comparable bid. When the RFQ includes the cable schedule, named certification scheme, line-item quantities, packing rules, and document package, the quotes can be firm and the technical reviews are faster. The buyer also gets a better record when the package arrives because the approved data already matches the purchase order.
Send the cable schedule, the required certificate scheme, and the line-item quantities to Warom at gm*@***om.com or call +86 21 39977076 / +86 21 39972657. Our engineers can check entry sizes, gland type, X conditions, and lead time against the package before you issue the formal tender.
Common Questions About Bulk Explosion Proof Cable Gland RFQs
How much cable detail do we need for an accurate bulk quote?
You need the cable outer sheath diameter and construction, plus the thread standard and zone classification for each line. A part number alone is not enough because the same gland model may be configured differently for armoured, screened, and unarmoured cable. In our quotations, missing cable construction is the main reason the price comes back as conditional. If the cable schedule is not ready, group the lines by known construction and ask for a preliminary budget, but do not treat that as a technical approval.
Should we accept a product family certificate or require a size-specific certificate?
Many buyers assume a family certificate proves every size is covered. That is not automatic. The certificate should state the product range, and the bidder should confirm which entries fall under each certificate number. For IECEx projects, we often reference a family certificate such as IECEx TUR 22.0035X, but the quotation still needs a line-by-line mapping. If your project requires size-specific documentation, put that requirement in the RFQ; otherwise some bidders will not include the extra review.
Does a high IP66 rating mean the gland is suitable for every hazardous area?
It depends on the protection concept and the installation. IP66 tells you about water and dust ingress protection. It does not state the gas group, temperature class, or the flameproof or increased safety protection method. A gland can be IP66 and still not fit a Zone 1 application if it is not certified for the required gas group or if the cable entry arrangement does not maintain the flamepath. The RFQ should therefore list IP rating separately from the hazardous area marking, so bidders can verify both.
Can we mix metric and NPT glands in one purchase order?
In projects we have handled, mixed metric and NPT entries appear more often than a single standard because equipment from multiple regions arrives on the same site. You can mix them in one order, but the RFQ must state which thread standard applies to each line. If the thread type is missing, you risk receiving parts that cannot be installed without adaptors. Share the cable schedule with Warom at gm*@***om.com and we will confirm the thread, entry size, and certificate for each line before the order is released.
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With over a decade of experience, he is a seasoned Explosion-Proof Electrical Engineer specializing in the design and manufacture of safety and explosion-proof products. He possesses in-depth expertise across key areas including explosion-proof systems, nuclear power lighting, marine safety, fire protection, and intelligent control systems. At Warom Technology Incorporated Company, he holds dual leadership roles as Deputy Chief Engineer for International Business and Head of the International R&D Department, where he oversees R&D initiatives and ensures the precise delivery of design documentation for international projects. Committed to advancing global industrial safety, he focuses on translating complex technologies into practical solutions, helping clients implement safer, smarter, and more reliable control systems worldwide.
Qi Lingyi